Begin by cooking your chicken—poaching is a great method, or use a store-bought rotisserie chicken for ease. Cool completely for 15 minutes, then shred into bite-sized pieces.

Finely dice your celery and chop the parsley for a better texture. Set the chopped vegetables aside.

In a large mixing bowl, combine shredded chicken, mayonnaise, Dijon mustard, salt and pepper. Fold in celery, pecans, parsley, lemon zest, and juice until well combined.

Spread the chicken salad mixture evenly on four slices of bread, topping with baby arugula. Cap with remaining bread slices.

Cut each sandwich in half and serve with fresh fruit salad or on a bed of crisp lettuce.